Dry-kiln.



PATENTED AUG. 28, 1906.

J. F., GLDFIBLD.

DRY KILN.

APPLICATION FILED JUNB 2 SHEETS-SHBET oo.oooon\oo oooooooo ooooooooo annum v4.

PATENTED AUG. 28, 1906.

J. E. OLDFIBLD.

mm KILN.

APPLICATION FILED JUNE5,1905.

2 SHEETS-SHEET 2.

@Human JOHN F. OLDFIEI'ID, BAL'IIMORE,` MARYLAND.

DIRYK'ILN.

Nofseensa.

Specification of Letters Patent.

Patented Aug. 28, 1906.

Application filed June 5, 3.905.A SerialNo. 263.746.

To all whom it may concern:

Be it known that I, JOHN F. OLDFIELD, a citizen of the United States, residing at Baltimore, in the State of Maryland, have invented certain new and useful Improvements in Dry-Kilns, of'which the vfollowing is a speciiica'tion. This invention relates to a drying-kiln.

The object of the invention is to improve kilns of that class where the material to be dried rests on trucks which are run into the kiln, the drying operation follows,-and then the trucks are run out of the kiln, whereby the time required for operation of drying will be shortened.

The invention is illustrated in the accompanying drawings, in which- Figure l is a vertical cross-section of a drykiln house, showing one form of the invention. Fig.2 is also a vertical cross-section of a dry-kiln house, showing a modified form of the invention. Fig. 3 is a vertical longitudinal section of the dry-kiln.

This dry-kiln may be used for drying or evaporating water from any material, but is intended princip allyfor drying green lumber. The operation involved in this kiln is the action on lumber of hot humid circulating air under slight ressure, which air in the course of its circu ation is repeatedly reheated, whereby a moist temperature considerably exceeding the boiling-point of water is maintained.

Referring to the drawings, Fig. 1, the Walls A may be made of any material. In the drawings they are shown made of wood. In the space between the internal sheathing b and the external sheathing. b is a suitable heat-insulating material c. The bottom and its connection with the Walls is tight. The roof D may have any preferred construction. Spaces or openingsg of some kind are provided for the escape of steam. The ceiling or to E is tight and has heat-insulating materia similar to the walls, but is provided with central vents or openings g for the esca e of steam from the drying-chamber B.

eretofore dry-kiln houses have had vertical passages or ducts formed in or against the walls, with the upper ends of the assages opened at and communicating with the top of the drying-chamber, and the lower ends opened below the heater on the bottom. In operation the hot moistened or saturated air passes from the top of the drying-chamber down these passages or ducts.

I found by observation that in kilns thus constructed, where the escape of saturated air was at'the top of the drying-chamber into the said down passages or ducts, the lower portion of the pile of lumber that was being dried in the chamber was always the last to become dry and that the time required to dry a truck-load-say ive thousand feet-oi` softwood, one-inch green lumber just from the saw, was about forty-eighthours.

As a result of experimentation I have found that by providing for the escape of the saturated air from the drying-chamber into the down passages or ducts at a point about midway of the height of said chamber, instead of at the top, as heretofore, the time required for the operation of drying is very ma' terially reduced, and that where forty-eight hours was required by the old constructionA less than twenty-four hours is required by the new construction.

Down passages or ducts I of ample size are formed on each side wall of the dry-,kiln chamber B. The upper ends 1'/ of these passages are Yopen or communicate with said chamber at a point whose vertical position is about midway between ceiling E and the track-rails F. The lower ends i2 of the passages open below the heater or steam pipes p. By thus arranging the top opening of the vertical passages or ducts about half-way upon the side walls of the drying-chamber the operation of the dryingchamber is greatly i mproved, because the circuit wi thin which the hot humid air circulates is shortened. Consequently 'the circulation is more rapid; .The lumber on the truck dries all over with equal rapidity, and the time required for drying is reduced one-half or more. This feature of vertical ducts with a short circuit may be used with or without a hooded ceiling in the chamber. Ir. Fig. 1 the hooded ceiling' is shown. It comprises a tight inner ceiling or false ceiling H below the outer or uppermost ceiling E, with a space k between the two, the inner sides H/ depending from said inner ceiling and extending downward along the side walls ofthe chamber. The distance downward to which they may depend may vary but said depending inner side must not ex`1 tend down so as to cover the upper openings i of the down passages or ducts. The inner sides H are spaced away from the internal sheathing?) of the side wall, and thereby form narrow passages or ducts Z for the escape of reheated moisture. These moisture-escape IOO IOS

ITO

passages -Zv communicate with the space 7c at I ratusfnear the bottom ofthe chamber and a the top and are relatively smaller in size than the down-passages Lnwhich difference in size contributes to the proper operation of the drying-kiln.

When the reheated moisture reaches the space 7c, it passes therefrom through the vent g under the roof and thence out at g'.

The air-tight ceiling, with depending sides tightly attached, forms a hood or tight cover within the top of the drying-chamber. Moisture or steam is conned by this hood and can escape from the drying-chamber only at the lower edge of the said depending sides .where the opening l to the upassageis found. By this combination the ormer op- -eration of this class of dry-kilnvis modified.

First, the hood retains the hotrnoisture at the top and around the upper part of the pile of lumber until it becomes excessive and creates a pressure and then it escapes at the o penconsiderably exceed the boiling-(point of water, the pressure thereby create at the vent-opening g in the top.

Y Referring now to Fig. 2, it maybe stated the construction is exactly the same asin Fig.v l except that`in Fig. 2 the hooded ceiling is absent. The more rapid circulation finds relief because of the short lower circuit is the same, V

andthe only difference is that the reheated moisture escapes directly from the dryingchamber B through the vent g instead of inrectly, as by the lip-passages in Fig. `l.

Having thus described my invention, what I I claim as new, and desire to secure by Letters Patent, is-

v1. A dry-kiln structure having walls'and bottom tightly connected; a roof; adr 'ng-y chamber; a ceiling between the drying-c am- .ber and roof and provided with a vent-opening communicating between the chamber and the space under the roof; a heater appalshort circuit for the circulation of hot humid I, whose highest ends, i', open from the drying-chamber at a point half-way up its vertical dimension and whose lowest ends open to 'said chamber below the said heater apparatus, as set forth.

2. A dry-kiln structure having walls and bottom tightly connected, and a roof; a ceiling and sides tightly joinedthereto and depending downward within the walls of the tical. escape-passages Whose openings from said depending sidesand lead therefrom to the space above the ceiling; a heater apparatus near the bottom of the chamber; and a are approximately half-way between the said said circuit comprising passages or ducts of size relatively larger than the said escapepassages and whose highest ends open from the drying-chamber below the lower ends of said escape-passages, and whose lowest ends open to said chamber below the heater appavratus, as set forth.

In testimony whereofI ax my signature in presence of two witnesses.

f JGHN F. OLDFIELD.

Witnesses:

CHARLES B. MANN, Jr.,

G. FERDINAND Voor.

air, said circuit comprising passages or ducts,

escape passages whose lowermost openings.

bottom and ceiling; a heater apparatus nearv the-bottom of the chamber; and a short circuit for the circulation of hot humid airstructure-said depending sides forming verthe drying-chamber are at the' lower edge of short circuit for the circulation of hot humid 

